(i) Precision: It is the measure of consistency or repeatability of measurements.
The closeness with which the individual measurements are departed or distributed about the average of number of measured value.
(ii) Drift: Drift means that with a given input the measured values changes with time. Perfect reproducibility means that the instrument has no drift.
(iii) Static Error: Static error is defined as the difference between the measured value and the true value of the quantity.
(iv) Dead Zone: Dead zone is the largest range of value of measured variable to which instrument does not respond. It is mainly due to friction in the instrument.